SE532152C2 - Method for monitoring refrigeration equipment - Google Patents

Abstract

Method for using a sensor (11) and a receiver (12) for monitoring a refrigeration system which has a compressor (1) and a pipe (8) which comes from the compressor and which conveys refrigerant. According to the invention, a temperature detector (13) of the sensor is disposed on top of the pipe in order to indirectly measure the temperature of the refrigerant, and a processor (17) of the sensor is used to calculate an operating state value, a cycle time and a load factor for the compressor based on the measured temperature, after which the sensor sends these values to the receiver.

Description

»Ii .M-.i fx! reach! 51.11 no: 2 in its interior may move completely as usual purely mechanically and also electrically show normal load.

The refrigerant circuit is usually physically extensive and consists of the compressor (Compressor), from which pipe installations for high-pressure gaseous refrigerant (HT Refrigerant gas), condenser (Condenser) usually placed outdoors, condensed refrigerant on the way to the various refrigerated containers, such as refrigerators / freezers, refrigerators / freezing gondolas (KB), the cooling packages (KP) inside the cooling containers where cooling is generated by the condensate taking heat from the objects to be cooled, and last of all the return of low-pressure cooling media gas (LT Cooling Gas) back to the compressor for compression.

On the high-pressure side, the wrong refrigerant leaks out to the surroundings, and on the low-pressure side, the wrong air leaks in. Both of these leaks lead to a gradual deterioration of the cooling system's cooling capacity.

These types of faults are very difficult for the end user to detect, because the thermostats compensate for the fault for as long as possible, and thus hide it, by calling for more cooling. Cooling media continues to leak and the cooling equipment becomes increasingly overloaded, this continues to an increasing extent until the thermostats constantly call for more cooling and the compressor works continuously during certain parts of the day. (Diagram, upper curve, 10: 00-18: 00) None of the usual methods yet detects or alerts this serious fault condition, but the degradation continues until the compressor, despite continuous operation, does not manage to keep the cold low enough, when conventional method 1 detects the fault, alternatively that the compressor fails due to the overload, then conventional method number 2 detects an error.

The invention, which solves this problem, among other things, without connections, can save large values. Food can be saved from destruction, refrigeration systems can be saved from collapsing, and the environment can be spared as a refrigerant leak can be detected earlier than usual.

There are large quantities of refrigeration compressors of varying age and condition, an ordinary medium-sized food store has, for example, 3-10 larger compressors, and in addition 10 smaller so-called plug-in compressors. There are thousands of grocery stores.

If an owner of a compressor plant wants to improve measurement, follow-up, and alarm, it is a difficult task without the invention, with large subsequent installation and conversion costs. The invention solves monitoring that currently available technology does not address by being able to be applied to existing compressor installations in a simple manner without connection or damage.

The invention constitutes a functional complement which is applied in the middle of hitherto known technology according to customary methods 1 and 2, respectively, described on the preceding pages. It enables monitoring of the function of existing installations by for the user in a simple way, by in-depth analysis of a single task, outgoing refrigerant temperature (GT), directly monitor the central component of a refrigeration system, the compressor. ššï 'EEE 3 The title invention enables a monitoring and detection of impaired, or absent, cooling function by connecting directly to the high-pressure pipe of the cooling compressor (HT Refrigerant gas), through temperature mapping (GT) of the at first sight contradictory, that a high temperature out of the compressor indicates that some form of cooling function may be delivered from the compressor, and by logical conclusions based on this temperature variation over time extract whether the compressor (Compressor) is working or stationary. From the condition of the compressor over time, certain parameters are further calculated, describing the function of the compressor, operating mode and degree of load. Based on these parameters, wireless (Radio) reporting and alerting is then finally given for detection.

The method places small demands on the device's temperature sensor (GT). The requirements of the method are so low that an ordinary standard temperature sensor attached to the outside of the compressor outlet pipe (HT Refrigerant gas) for refrigerants in high-pressure gas form is completely sufficient.

This ease of installation is also unique and important for the following; - Sensor can be connected by a person without high current authorization, with little knowledge.

- Original supplier of refrigeration equipment, incl. compressor, cannot successfully claim that warranty commitments are affected or should cease to apply, based on damage to delivered equipment.

- The refrigeration system owner can apply a detection regardless of the original refrigeration equipment connection, configuration, or supplier. A device-technically independent, unaffected device function or legal commitments / obligations are achieved.

After installation, delivery or cooling service, the user can, in a simple way with the invention, ascertain the quality and effect of the measure taken, by simply studying the parameters central to the system's function, which are communicated by the invention.

The sensor (GT) measures the temperature (Diagram, top curve) and the equipment (P) connected to the sensor can, based on the temperature variation in time (Clock), draw conclusions about the function of the compressor and based this on the earliest possible alarm that the function of the cooling equipment does not is as it should be. This alarm is transmitted (TX) wirelessly in a radio message (Radio) to a receiver (Receiver) for further use.

In practice, the equipment is designed as a completely wireless sensor containing the method for analyzing the temperature variation, power supply with built-in battery (Batt) and the extracted parameters are transmitted to a measured value receiver for further recovery. The installation takes in practice 15-30 minutes, after which the invention begins to analyze "its" compressor tube to deliver useful information about the function and parameters of the compressor within 24 hours. As the method is not sensitive / critical, useful parameters can be obtained immediately after installation if the equipment on delivery contains reasonable starting values in its memory (M).

This method, in contrast to current technology, can also collectively detect the compressor's inability to deliver cold for whatever reason; Power outages, phase loss saw tea off. 4 (Electricity), fault in control & regulating equipment (Cooling control), fault in compressor (Compressor), or fault in the refrigerant circuit.

Finally, the apparatus and method enable the earliest possible detection of the condition that refrigeration is not delivered in the required quantity from the refrigeration compressor to the refrigeration unit (KB) with its stored food (KO). This increases the possibility of a successful emergency response to save food from destruction or in the best case that emergency response can be completely avoided by detecting faults in such good time that service during normal working hours can be called before the plant's function has decreased so much that the cold can no longer be maintained. .

The invention will be described in more detail below with reference to the accompanying drawings.

Figure 1 shows an embodiment of an apparatus according to the invention.

Figure 2 shows a curve measured with an apparatus according to the invention.

The apparatus has a temperature sensing body (GT), which may be in relation to the apparatus internally or externally, intended for the surface to be attached without intervention to the outside of the compressor outlet line for high-pressure gas (HT Cooling Gas).

The attachment takes place practically a short distance away, about 500 mm from the compressor body, so that the dynamic temperature course is not reduced by the thermal mass / inertia in the body of the compressor consisting of cylinder, piston, etc. The sensor body (GT) is connected to the device's electronics and processor (P) which analyzes the temperature variation over time.

The processor (P) follows the temperature and can, based on the temperature variation in time with the help of a clock (Clock) according to the method of the invention, draw conclusions about the function of the compressor. These conclusions, parameters describing the operation of the compressor, are stored in the device's memory (M).

The temperature is monitored (Diagram, top curve), continuous or smoothing with a short sampling time in relation to the included time constants, and a dynamic minimum resp. max value over one or fl your days is kept alive. If the maximum value exceeds a certain temperature, abnormal working conditions prevail and alarms are issued for this.

In practical operation, a compressor can vary between being in different states; - Normal operation, with periodic on / off connections of thermostat.

(Diagram, top curve, 00: 00-08: 00) - Very heavily loaded, mostly continuous operation with a few short disconnections.

(Diagram, top curve, 08: 00-10: 00) - Overloaded / undersized / leakage in the cooling circuit, continuous operation. flfi agram, top curve, 10: 00-18: 30) - Defrost cycle, completely disconnected to thaw ice on the cooling packages.

(Diagram, top curve, 18: 30-19: 30) - Heavily loaded, with periodic thermostatically controlled driving, mostly to.

'S52 5 (Diagram, top curve, 21: 00-00: 00) The method and the apparatus follow the change in temperature over time, based on the temperature a derivative is made, which expresses the rate of change of temperature. This derivative is positive when the compressor has started, and negative when it has stopped. Typical maximum derivative values, immediately after start / stop, are 10 degrees per minute.

Mathematically, this can be expressed thus; (TfTh) = temperature derivative (tfth) Tn temperature, current.

Th temperature, historical previous measurement. In time, current. th time, historical previous measurement.

Theoretically, this temperature derivative is always positive as long as the compressor is working, but in practice after a long working time the temperature will vary slightly around a working temperature for continuous operation. (Diagram, top curve 12: 00-14: 00) To handle this so that the method does not falsely signal compressor stop at continuously operating compressor, or vice versa at stationary compressor, an additional term is introduced; temperature derivatives + ((Tn- TmedeQ / K) Tn temperature, current. If the sampling times in the practical realization of the method are long, Th should be used instead, this because this temperature in the method's formula shows "from where" the temperature change begins .

Tmede] average temperature of highest and lowest occurring T.

Practical operation usually has maximum temperatures around 80 degrees and minimum around 20 degrees, resulting in a T means of about 50 degrees. The method has the advantage of low device requirements, which means that even these values are not critical but can vary + -10% without disturbing the method's results.

K constant in order for the method to have a margin against error display caused by temperature fluctuations at constantly operating and constantly stationary compressor, respectively. An outside LT? i,. | l "~. ,, l å !! Lil get 6 practical circumstances selected value of 8 gives that sudden temperature fl actuations of up to 3.75 degreesfminute on continuously running and stationary compressor should not give incorrect operating indication. An increased value of K gives faster response , but increased risk of false values and vice versa.

The result of this formula is in practice unequivocally positive for a working compressor, and unequivocally negative for a stationary compressor. (Diagram, middle curve, Y-axis with scale values to the right) In addition to a certain, in practice inevitable, and set in relation to other time perspectives, negligible time delay.

Based on this, the following logical decisions are formulated in the apparatus in the processor (P) or with electronic execution in comparator logic; If formula value> 0, then the compressor is working If formula value <0, then the compressor is stationary (Diagram, bottom curve, läill = working, 0 = from = stationary) This logic, leading to the knowledge of whether the compressor is working or is stationary, is used as further in the further processing of the device / method.

The device is designed so that it has knowledge of the time (Clock) and measures the times for the two different states. The latest time extension for a period of working compressor is stored in the device's memory (M), as well as the latest time extension for a period of downtime. Based on these two values, cycle time and degree of load are calculated, usually in technical terms called duty cycle.

Cycle time = working time + downtime.

Load ratio = working time / cycle time The load ratio is an analogous number between 0 and 1, where low values mean low-loaded / utilized compressor, and where high values mean a highly loaded / utilized compressor, with l as the highest value indicating a continuously operating maximum-loaded compressor. These parameters are not exemplified in the diagram, but are only exemplified in text by the word choices in the text above; For example; 0.0 = defrost, stationary 0.5 = normal operation 0.7 = heavily loaded 0.9 = very heavily loaded 1.0 = overloaded Based on these parameters describing the operation of the compressor, the apparatus gives the following assessments or operating conditions; - If the downtime becomes predominant, exceeds the maximum permitted downtime, compressor downtime is assumed, this includes all the underlying causes, and alarms reflecting this are issued. 7 - If the time indicates that the compressor is constantly running, congestion or too small capacity is assumed, and alarms reflecting this are issued.

- If the cycle time becomes too short, reflecting control equipment with too little terinostathy hysteresis, an alarm is issued for this.

- In addition to pure alarming, the equipment's calculation of duty cycle is very good information about the system's structure and function, where low values indicate a low load, possibly oversized, compressor and where opposite high values of a new plant indicate heavily loaded undersized compressor, alternatively that after a certain time, there has been a leakage of refrigerant or leakage of air which gradually impairs the function of the system so that the compressor gradually becomes more and more loaded.

If and when the processor (P) has thus established that the compressor does not deliver cooling in the right way or to the required extent to the cooling furniture (KB), a larin message (Radio) is sent out wirelessly (Tx) to the receiver (Receiver) for further transport. In addition to pure alarms, the equipment with its built-in radio transmitter (Tx) also regularly broadcasts radio messages (Radio) containing continuous operational information, consisting of the calculated parameters described above.

All this, completely wireless, without connection to, or influence on, existing refrigeration equipment.

According to an embodiment of the invention, a method and apparatus for measuring, analyzing and monitoring the temperature of the gas coming from a refrigeration compressor (Compressor) is generated to extract therefrom information on the connection, disconnection, operation and cooling capacity of the refrigeration compressor relative to thermostats or similar units. urgent needs. This monitoring of the cooling function is done without measuring either the temperature in the cooling container (KB), the temperature at the cooling package (KP) or the temperature of the cooled objects (fl šO) as is usual. Furthermore, the monitoring takes place without electrical connection in the cooling control equipment (Cooling control), where monitoring is usually carried out of electrical conditions (Electricity) included in the compressor's electric driving motor (Electric motor).

Finally, the monitoring takes place without any pressure, levels, fates, movements, vibrations, or sounds, in the compressor or circuits connected to the compressor, having to be measured.

The method and equipment enable monitoring of dangerous refrigeration equipment without the need for any intervention in the existing equipment.

According to another embodiment of the invention, a method and apparatus for monitoring the connection, disconnection, and cooling function of the refrigeration compressor are produced without electrical connection of any kind, without intervention in existing refrigeration equipment, and without the need to make adaptations to the invention in now produced refrigeration equipment. The monitoring takes place by measuring the temperature of the high-pressure gas coming from the refrigeration compressor (HT Refrigerant gas). Further characteristic is that the method only needs one measuring point, and that this measurement made by the apparatus does not have to be accurate, a non-intervention measurement of the temperature with a sensor (GT) applied to the outside of the pipe leading the high pressure gas from the compressor is sufficient.

According to a further embodiment of the invention, an analysis is made of how the temperature of the high-pressure gas varies over time. (Diagram, top curve) This analysis 8 is performed in equipment located at the compressor, in receiving equipment or elsewhere.

This analysis is done so that the derivative of the temperature variation over time, in other words temperature changes in degrees per unit time, with the addition of a linear component, proportional to the instantaneous value of the temperature, balanced around a midpoint, approximately midway between maximum and minimum temperature. (Diagram, middle curve. Axis with Y-values to the right.) When the result of this mathematical operation is positive, this indicates that the compressor is currently in operation. Conversely, if the result is negative, it indicates that the compressor is currently stationary.

Based on this, a digital parameter is created that can have the values 0 or 1, representing a stationary compressor, alternatively a working compressor. (Diagram, bottom curve) According to one embodiment of the invention, the analysis is performed at each individual time, or at discrete sampling time points, according to the following mathematical formula; (TfTh) + Th 'Tmedelylš) (tfth) Tn temperature, current.

Th temperature, historical previous measurement. in time, current. th time, historical previous measurement.

Mean mean temperature calculated from maximum and minimum, for a few days, occurring T.

K constant fi causes the method to have a margin against erroneous results caused by normally occurring temperature fluctuations at constant running or constantly stationary compressor.

According to an embodiment of the invention, the constant K is in the range 2 to 30.

According to an embodiment of the invention, the temperature variation of the high pressure gas (HT Refrigerant Gas) coming from the refrigeration compressor is analyzed over time by a processor (P) where the result of the invention method is a digital variable indicating the logical end result, whether the compressor is stationary or in operation.

According to an embodiment of the invention, the temperature variation of the high-pressure gas (HT Refrigerant Gas) coming from the refrigeration compressor over time is analyzed by electronics included in the apparatus, where different spheres represent numerical values and where finally a sperm indicates the logical end result, whether the compressor is stationary or in operation.

According to an embodiment of the invention, the temperature of the high-pressure gas (HT Refrigerant Gas) coming from the cooling compressor is measured with an abutment temperature sensor (GT). According to an embodiment of the invention, the refrigerated container (KB) is one or two refrigerators, freezers, freezers, refrigerated gondolas, freezing gondolas, cold rooms, freezing rooms or refrigerated / frozen transport vehicles for storage, storage, transport or sale of refrigerated objects (KO). of food.

According to an embodiment of the invention, the result is used from the calculation of the method whether the compressor is switched off or switched on, further to using switched-off clock (Clock) to calculate switched-off time and switched-on time. From these, cycle time is further calculated as disconnected time plus switched-on time. From these parameters, the degree of utilization, the degree of load, or expressed as a professional duty cycle, is further calculated by calculating the ratio of connected time / cycle time. These parameters provided by the method are stored in the device's memory (M). Based on the values of these parameters, different types of operating indications and alarms are also issued, indicating different types of normal or incorrect conditions in the operation or function of the refrigeration compressor.

According to an embodiment of the invention, the result of the method analysis of the temperature of a wireless device consisting of a radio transmitter (Tx) built into the device, which transmits messages (Radio), containing the information, parameter values and alarms, is transmitted to a radio receiver (Receiver), for further utilization.

According to an embodiment of the invention, the apparatus does not need applied voltage to function, but operates for a longer period of time by means of energy coming from a battery (Batt), accumulator, capacitor or equivalent energy storage component installed in the apparatus.

Claims (2)

10 15 20 25 30 35 P A T E N T K R A V Method for using a device comprising on the one hand a sensor, comprising a temperature sensor (GT), a processor (P), a memory (M), and a radio transmitter (Tx), on the other hand a receiver for receiving radio messages from [drawing sheet 11 , non-invasive [318-319] monitoring an existing sensor radio transmitter (Tx) refrigeration equipment comprising a compressor and a high pressure refrigerant flowing from the compressor and flowing in a pipe [326], which method comprises the steps of: - arranging the temperature sensor (GT) outside the pipe [lll] to measure the temperature of the high pressure refrigerant [l67], - that the temperature is sampled at a predetermined sampling frequency [176 and 3461, - that the minimum and maximum temperature value for the last day or days is kept alive [177], - that the processor (P) , for each sampled temperature value, calculates a value according to: (Tn "Th) / Üln-th) + (Tn" T average) / K [220] or (Tn "Th) / (tn'ïn) + (Tn" Tmam1) / K [223 “224] where Tn is the last sampled temperature value, Th is the previous sampled e is the temperature value, tn is the sampling time of the last sampled temperature value, th is the sampling time of the previous sampled temperature value, Tmaæl is the average temperature of said lowest and highest temperature value (356-357] and K is a constant in the range 2-30 [363-3641, 10 15 20 25 30 35 2. that the processor (P), for each calculated value, determines whether the value is positive or negative, the processor (P) associating positive values with the compressor working and negative values with the compressor being stationary [251-253 and drawing sheet 2], that the time extension for the last period of working compressor and the time extension for the last period of stationary compressor [255-2601, that the cycle time of the compressor is calculated according to: determined and stored in a memory (M) working time + downtime [263] and that a load rate for the compressor is calculated according to: working time / cycle time [264] where working time is equal to the time extension for the last period with working compressor, and downtime is equal to the time extension for the last period with stationary compressor [258-2601, and that alarms or reviews about the compressor are based the downtime, working time, cycle time or load rate is sent to the receiver [280-3021. Method according to claim 1, characterized in that the temperature sensor (GT) is arranged on the outside of the pipe approximately 500 mm from the compressor body of the compressor [164]. P2l08SE TF0l 070921